The operational amplifier of this circuit can be the 741. The circuit has very low consumption and can be powered by two 9-B batteries. Low voltage amplifiers can be used.
This circuit is recommended for alarm systems since it has a good output stage. The circuit is...
) Suggested by Philips in a 1968 documentation this circuit has very high 10 ohm on-load voltage...
No information is given about the transformers in this circuit suggested by Motorola in a 1968...